1. Field of the Invention
This invention relates to a method for producing of a novel phthalocyanine compound. More particularly, it relates to a method for producing of a phthalocyanine compound which has an absorption in a near infrared zone and exhibits high solubility to solvents. Since the phthalocyanine compounds to be obtained by the method of the production according to the present invention have absorption in the near infrared zone of 600-1000 nm, they manifest excellent effects when they are used as near infrared absorption materials e.g. near infrared absorption dyes, near infrared sensitizers, thermal transfer inks, photothermal conversion agents for thermosensible papers and screen printing papers, PDP grade near infrared absorption filters, asthenopic preventives, and photoconductive materials intended for the operation of writing or reading in optical recording devices, liquid crystal display devices, and optical character reading device which utilize a semiconductor laser or as color separation filters for image pickup tubes, color filters for liquid crystal display, selective absorption filters for color braun tubes, color toners, flush fixing grade toners, thermal jet grade inks, indelible bar code inks, microbe-inactivating agents, photosensitive dyes for the therapy of ulcers, and heat ray insulators or heat retaining agents for automobiles or building materials. The phthalocyanine compounds which are obtained by the method of the production according to this invention manifest outstanding effects particularly when they are used as optical recording media e.g. compact discs, laser discs, optical memory discs, and optical cards, liquid crystal display grade color filters, PDP grade near infrared absorption filters, or heat ray insulators.
2. Description of Related Art
The recent years have been witnessing active development of such optical recording media as compact discs, laser discs, optical memory discs, and optical cards which utilize the semiconductor laser as their light sources. Particularly, CD, PHOTO-CD, and CD-ROM have been being used in large quantities as digital recording media of high capacity and rapid access for the storage and regeneration of voices, images, and coded data. These systems invariably necessitate so-called near infrared absorption dyes which are sensitive to the semiconductor laser. As regards these dyes, the desirability of their having excellent characteristics has been finding widespread recognition. Such phthalocyanine compounds as are stable enough to resist light, heat, and excellent in strength, among other species of phthalocyanine compound, are now undergoing numerous studies which are devoted to imparting thereto the solubility in solvents which is needed to suit the purpose for which the compounds are used. Specifically, methods for forming thin films of dyes without requiring such complicated steps as vacuum deposition or dispersion in resin, methods for selectively using such solvents as are incapable of corroding substrates used in the relevant devices being manufactured, and methods for enabling dyes to be solved in high concentrations in various species of solvents fit for various applications in the light of the fact that they also dissolve in the resins being used have been the subjects for such studies.
The so-called grazing materials for use in buildings or vehicles are in need of a light-shielding agent which is capable of intercepting heat rays. Since phthalocyanine compounds are rich in resistance to heat and lightfastness, they have been proposed in numerous types. Further, phthalocyanine compounds of varying types have been proposed for use as dyes in liquid crystal display grade color filters and in PDP grade near infrared cut filters.
Orthophthalonitrile is reacted with a metal source in a synthesis of a method for phthalocyanine compounds by using orthophthalonitrile. As the metal source, generally, halogenide, oxide, salt of organic acid, metal powder are cited. Among them, halogenide is used to the reaction because of having high reactivity generally. There were, however, some problems that halogen atoms were mixed to a skeleton of phthalocyanine, or an equipment made of special material was needed because of generation of halogen gas by using halogenide of the reaction for synthesis of phthalocyanine. Instead of it, a means for synthesizing the phthalocyanine compound, the method which use an oxide as a metal source is also proposed. There are examples of producing a vanadyl phthalocyanine by using vanadium pentaoxide(JP-A-06-256680, JP-A-07-36205, U.S. Pat. No. 4,771,133, Jp-A-03-269063, U.S. Pat. No. 4,557,868 and JP-A-06-41137). Among them, although JP-A-06-256680 and JP-A-07-36205 were disclosed a method which used .alpha.-chloronaphthalene as solvent, it had a problem that yield of vanadyl phthalocyanine didn't raise because of lower solubility based on little solubility to .alpha.-chloronaphthalene. On the one hand, U.S. Pat. No. 4,771,133, JP-A-03-269063, U.S. Pat. No. 4,557,868 and JP-A-06-41137 were disclosed a method which used ethylene glycol as solvent, the method was reacted with an intermediate of causing the reaction with phthalonitrile and ethylene glycol. Certainly this method raised a reactivity for using an intermediate, it had a problem that a purification process was complicated because of an inferior selectivity to produced phthalocyanine compound.
In recent years, a phthalocyanine compound having high solubility in solvents was desired, a general method to solve the problem to displace the extent of a bulky substituent onto benzene ring of a skeleton of phthalocyanine. There was no example using a metal oxide as a source metal for synthesis of phthalocyanine compound having the extent of a bulky substituent. It is because that the orthophthalonitrile compound having a little bulky substituent has an inferior reactivity comparing to orthophthalonitrile compound having no or smaller substituent because of a stereo impediment. For overcoming the issue, a high reactivity of halogenide would be used for synthesis of the phthalocyanine compound having the extent of a bulky substituent. Using a halogenide, there were problems that a substituent was reacted with halogen atoms, and the natural property of phthalocyanine compound was damaged because of bonding a halogen atom to skeleton of phthalocyanine compound. Accordingly, a development for synthesis of phthalocyanine compound using a metal oxide compound as a metal source was desired.
It is, therefore, an object of this invention to provide a method for producing a phthalocyanine compound, which is characterized by causing an orthophthalonitrile compound possessable of a substituent to react with a metal oxide in the presence of a compound forming in the aqueous solution thereof at 25.degree. C. an acid or conjugate acid having a dissociation index pKa (the logarithmic value of the reciprocal of the dissociation constant of the acid or conjugate acid) of not more than 7.0. Specially to provide a useful method for producing a phthalocyanine compound having substituent capable of increasing a solubility.
Another object of this invention is to provide a method for the production of a phthalocyanine compound possessable of a substituent, which compound excels in yield and purity.